Electric circuit breaker with shunt trip coil



ELECTRIC CIRCUIT BREAKER WITH SHUNT TRIP 0011,

Filed Feb. 15, 1965 A ril 1, 1969 E. P. DESSERT Sheet of 1 44 I. llll' A Ji /mf aiward jwsar 5 @Mz mm,

' Filed Feb. 15, 1965 April 1969 E. P. DESSERT 3,436,695

ELECTRIC CIRCUIT BREAKER WITH SHUNT TRIP COIL Sheet 3 of2 United States Patent Office 3,436,695 ELECTRIC CIRCUIT BREAKER WllTl-l SHUNT TRIP COIL Edward 1. Dessert, Cedar Rapids, Iowa, assignor to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed Feb. 15, 1965, Ser. No. 432,656 Int. Cl. H0111 77/02, 75/12 US. Cl. 335-9 9 Claims This invention relates generally to electric circuit breakers, and more particularly to a circuit breaker having a plurality of side-by-side compartments defined by a plurality of separately molded casing portions secured to each other, one of the compartments having a shunt trip coil therein operable to trip circuit breaker mechanisms in the other compartments.

An object of the invention is to provide a circuit breaker having a casing formed of a plurality of separately molded casing portions secured to each other and collectively defining a plurality of side-by-side compartments, all but one 'of the compartments each having a circuit breaker mechanism therein and the remaining compartment having a remotely controllable shunt trip coil therein, the coil being energizable to effect unlatching of a trip lever and thereby operate a common trip bar to trip the circuit breaker mechanisms in the other compartments and open their respective pairs of separable contacts, and the coil being disposed in a space in its compartment corresponding respectively to spaces in the other compartments eneompassing the contacts therein.

Other objects of the invention will appear when the following specification is considered together with the accompanying drawings in which:

FIG. 1 is a side elevational view of a circuit breaker constructed in accordance with my invention;

FIG. 2 is an end elevational view of the circuit breaker of FIG. 1;

FIG. 3 is an enlarged sectional view taken generally along the line 33 of FIG. 2;

FIG. 4 is an enlarged sectional view of the circuit breaker of FIG. 1 taken generally along the line 44 of FIG. 2;

FIG. 5 is a perspective view of the electromagnetically operable actuating means of the actuating mechanism of FIG. 4;

FIG. 6 is an end elevational view of the actuating means of FIG. 5; and

FIG. 7 is a sectional view taken generally along the line 77 of FIG. 6.

A circuit breaker 10 constructed in accordance with the invention includes a casing formed of a plurality of separately molded casing portions secured to each other and collectively defining a plurality of side-by-side compartments. In the embodiment of the invention shown, four casing portions 12, 13, 14, and are provided.

The casing portion 15 forms a base for the mechanism shown in FIG. 4 and hereinafter described. One side of the casing portion 14 forms a cover for the casing portion or base 15 and cooperates with the casing portion 15 to define a compartment for the mechanism shown in FIG. 4. The other side of the casing portion 14 forms a base for the mechanism shown in FIG. 3 and hereinafter described. One side of the casing portion 13 forms a cover for the base side of the casing portion 14 and cooperates with the casing portion 14 to define a compartment for the mechanism shown in FIG. 3. The other side of the casing portion 13 forms a base for a mechanism like that shown in FIG. 3. The casing fortion 12 forms a cover for the base side of the casing portion 13 and cooperates with the casing portion 13 to define a compartment for the mechanism like that shown in FIG. 3. The four cas- Patented Apr. 1, 1969 ing portions 12, 13, 14, and 15 thus define three side-byslde compartments and are secured together as by a plurality of rivets 16.

The mechanism in a first and a second of the side-byside compartments respectively defined by the casing portions 12 and 13 and by the casing portions 13 and 14 are circuit breaker mechanisms essentially like those of US. Patent No. 2,889,428, to which reference may be had for a more complete description. The circuit breaker mechanism in the compartment defined by the casing portions 13 and 14 is shown in FIG. 3 and includes a plug-in type line terminal member 18 having a stationary contact 19 secured to an inner end portion thereof, a pivotally mounted operating handle 20, a movable contact arm 22 pivotally mounted adjacent one end in a pair of spaced depending leg portions of the handle 20 and having a movable contact 23 adjacent the other end, a releasably latchable trip lever 24 pivotally mounted on a pin portion 25 of the casing portion 14, a tension spring 26 connected adjacent one end to the contact arm 22 and adjacent the other end to the trip lever 24, a load terminal strap 28 provided with a clamping screw 29, a bimetallic strip 30 secured adjacent one end to an inner end portion of the terminal strap 28 and having a generally U-shaped magetizable core 32 secured to its other end portion, a braided conductor 34 having one end portion secured between the bimetallic strip 30 and the core 32 and its other end portion secured to the contact arm 22, an armature member 36 pivotally mounted on the core 32 and releasably latching the trip lever 24, a com pression spring 38 biasing the armature 36 away from the core 32, a generally U-shaped ambient temperature compensating bimetallic member 40 having one leg portion secured to the armature 36 and its other leg portion loosely overlapping the core 32, a calibrating screw 42 for resiliently deforming the terminal strap 28 to vary the amount of latching engagement between the trip lever 24 and the armature 36, a mounting clip 44 opposite the line terminal'lil, a stack 46 of arc plates adjacent the contacts 19 and 23, an arc shield 48 of insulating material hooked to the movable contact arm 22, a first pin 50 carried by the trip lever 24 and cooperable with the handle 20 to effect the relatching of the trip lever, and a second pin 52 carried by the trip lever 24 and engaged, in a latched position of the trip lever, with a biasing spring 54 for a pivotally mounted trip bar and armature actuating lever member 56, the pin 52 also being engageable, upon movement of the trip lever away from the latched position, with an outer end portion of the lever member 56.

The circuit breaker mechanism in the compartment defined by the casing portions 12 and 13 is exactly like the circuit breaker mechanism shown in FIG. 3, except that instead of having-an operating handle like the operating handle 20 with its outwardly projecting portion, the mechanism between the casing portions 12 and 13 is provided with a pivotally mounted inner member 20a like that shown in FIG. 4 for the actuating mechanism in the third compartment defined by the casing portions 14 and 15. The inner members 20a are tied to the handle 20 for manual operation as a unit therewith by means of a handle tie bar 58 extending through and keyed to the handle 20 and inner members 20a.

The two circuit breaker mechanisms are also tied together for automatic operation as a unit upon flow of excessive current through either. Thus, the pivotally mounted trip bar and armature actuating lever members 56 are tied together for operation as a unit by means of a common trip bar 60 extending through and keyed to the lever members 56. Upon flow of a sustained moderate overload current through the bimetallic strip 30' of either of the circuit breaker mechanisms, deflection thereof causes counterclockwise (as viewed in FIG. 3) movement of the respective core 32, ambient temperature compensating bimetallic member 40, and armature 36 about the upper end of the bimetallic strip 30 and releases the respective trip lever 24. Also, upon flow of a high overload or fault current through the bimetallic strip 30 of either of the circuit breaker mechanisms, the respective armature 36 is attracted toward its core 32 and releases the respective trip lever 24. The trip lever 24 of each circuit breaker mechanism is thus provided with a thermally and magnetically responsive tripping means including the respective bimetallic strip 30, core 32, armature 36, and bimetallic member 40'.

The release of the trip lever 24 of either of the circuit breaker mechanisms, biased clockwise (as viewed in FIG. 3) by its spring 26, causes movement of the upper end of the spring 26 to the opposite side of the pivotal connection between the respective contact arm 22 and the handle or inner member 20a, to elfect disengagement of the respective movable contact 23 from the respective stationary contact 19. The release of the trip lever 24 also causes movement of the respective pin 52 into engagement with the respective lever member 56 to effect pivotal movement thereof counterclockwise (as viewed in FIG. 3), and, through the common trip bar 60, to also effect pivotal movement of the lever member 56 in the other of the circuit breaker mechanisms. The pivotal movement of the lever member 56 in the other circuit breaker mechanism causes it to engage and pivot the respective armature 36 to release the respective trip lever 24 and thereby disengage the movable contact 23 of the other circuit breaker mechanism from its respective stationary contact 19. Thus, the pairs of contacts of both circuit breaker mechanisms are opened upon flow of excessive current through either pair.

In accordance with this invention, the contacts of both circuit breaker mechanisms are also opened upon operation of the actuating mechanism shown in FIG. 4 and disposed in the third compartment defined by the casing portions '14 and 15. The actuating mechanism does not include a pair of separable contacts like the contacts 19 and 23 of the circuit breaker mechanisms, and it is not intended to operate in response to overload currents as do the circuit breaker mechanisms. Nevertheless, the actuating mechanism does contain a number of parts identical to parts of the circuit breaker mechanisms and other parts analogous to parts of the circuit breaker mechanisms. Thus, a releasably latchable trip lever 24 of the actuating mechanism is pivotally mounted on a pin portion 25 of the casing portion 15 and biased toward an unlatched position by a spring 26. A terminal strap 28a is included in the actuating mechanism and is provided with a clamping screw 29a for the securing of a lead wire of a control circuit thereto. A conductive strip 30a, shaped like the bimetallic strip 30 but not made of bimetal, is secured adjacent one end to an inner end portion of the terminal strap 28a and has a generally U-shaped support member 32 secured to its other end portion. A latching member 36 is pivotally mounted on the support member 32 and releasably latches the trip lever 24. For convenlence, the support member 32 and latching member 36 may be identical to the core 32 and armature 36 of the circuit breaker mechanisms, although it is not necessarily intended that the latching member 36 be attracted toward the support member 32 by the flow of current through the conductive strip 30a. A compression spring 38 is provided to bias the latching member 36 toward a latching position. A generally U-shaped stop member 40a, shaped like the ambient temperature compensating bimetallic member 40 but not made of bimetal, has one leg portion secured to the latching member 36 and its other leg portion loosely overlapping the support member 32 to limit movement of the latching member 36 away from the support member 32. A calibrating screw 42 is provided for resiliently deforming the terminal strap 28a to vary the amount of latching engagement between the trip lever 24 and the latching member 36. A first pin 50 is carried by the trip lever 24 for cooperation with the inner member 20a in the relatching of the trip lever. A second pin 52 is carried by the trip lever 24 for engagement in a latched position of the trip lever with a biasing spring 54 for a pivotally mounted trip bar actuating lever member 56 and engageable upon movement of the trip lever away from the latched position with an outer end portion of the member 56.

The actuating mechanism of FIG. 4 includes electromagnetically operable actuating means for effecting movement of the latching member 36 to release the trip lever 24, the actuating means being shown in detail in FIGS. 5, 6, and 7 and including a generally L-shaped magnetizable bracket 62 held in position between the casing portions 14 and '15. The bracket 62 includes a shorter leg portion 62a, a longer leg portion 62b, a tongue 62c sheared and bent outwardly from the longer leg portion 62b, and a tongue 62d on the free end portion of the longer leg portion 62b. The tongue 62c is provided with an aperture 629 which receives an end portion of the spring 26. A generally rectangular electrical coil 64 wound on a bobbin 65 and a generally rectangular magnetizable core 66 disposed in the bobbin 65 are secured to the shorter leg portion 62a as by a screw 67 threaded into the core 66. The coil 64 and core 66 are disposed in a space in the third compartment which corresponds respectively to spaces in the first and second compartments encompassing the pairs of contacts 19 and 23 therein. A generally flat armature member 68 is provided with a slot for receiving the tongue 62d upon which it is pivotally mounted. A tension spring 70' is provided to bias the armature member 68 counterclockwise, as viewed in FIG. 4, about the tongue 62d. One end of the spring 70 is hooked to the spring 26 and the other end of the spring 70 is hooked to the armature member 68. A driving screw 72 is adjustably mounted in the armature member 68 to drive the latching member 36 toward the support member 32 and release the trip lever 24 upon attraction of the armature member 68 toward the core 66. A stop 74 formed as a projecting part of the casing portion 15 serves to limit pivotal movement of the armature member 68 away from the core 66. One lead wire 76 of the coil 64 is electrically connected to the support member 32 and another lead wire 78 of the coil 64 is electrically connected to one end of a resistor 80 the other end of which is electrically connected to a second terminal strap 82 provided with a clamping screw 83.

When the potential diflerence in a control circuit having opposite sides connected respectively to the terminal straps 28a and 82 exceeds a predetermined value, the magnetic flux produced in the core 66 by the current in the coil 64 overcomes the spring 70 and attracts the armature member 68 into engagement with the core 66, whereupon the driving screw 72 moves the latching member 36 to release the trip lever 24. The movement of the trip lever 24 away from latched position under the influence of the spring 26 causes the pin 52 to pivot the trip bar actuating lever member 56 and the common trip bar 60 to trip the circuit breaker mechanisms in the other two compartments, the pivoting of the common trip bar 60 also pivoting the members 56 in the other two compartments to move the respective armatures 36 toward their cores 32 to release the respective trip levers 24 and open the respective pairs of contacts 19 and 23.

Various modifications may be made in the structure disclosed without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. A molded-case electrical circuit breaker comprising a casing having at least two side-by-side compartments each having a pair of opposite ends, a pair of separable contacts disposed in a first of said compartments adjacent one end thereof, tripping means disposed in said first compartment adjacent the other end thereof, said tripping means being operative to effect separation of said contacts upon flow of excessive current therethrough, and actuating means disposed in a second of said compartments, said tripping means also being operable to effect separation of said contacts upon operation of said actuating means, said actuating means including an electrical coil disposed in said second compartment adjacent one end thereof corresponding to said one end of said first compartment, and said coil being energizable to effect operation of said actuating means and tripping means and separation of said contacts upon occurrence of a predetermined potential difference across said coil.

2. A molded-case electrical circuit breaker comprising a casing having at least three separately molded casing portions secured to each other and collectively defining at least two side-by-side compartments each having a pair of opposite ends, two of said casing portions respectively forming a pair of opposite outer side walls of said casing and a third of said casing portions forming an intermedi ate wall between said two compartments, a pair of separable contacts disposed in a first of said compartments adjacent one end thereof, tripping means disposed in said first compartment adjacent the other end thereof, said tripping means being operative to effect separation of said contacts upon flow of excessive current therethrough, and actuating means disposed in a second of said compartments, said tripping means also being operable to effect separation of said contacts upon operation of said actuating means, said actuating means including an electrical coil disposed in said second compartment adjacent one end thereof corresponding to said one end of said first compartment, and said coil being energizable to effect operation of said actuating means and tripping means and separation of said contacts upon occurrence of a predetermined potential difference across said coil.

3. A molded-case electrical circuit breaker comprising a casing having four separately molded casing portions secured to each other and collectively defining three sideby-side compartments each having a pair of opposite ends, two of said casing portions respectively forming a pair of opposite outer side walls of said casing and each of the other two of said casing portions forming an intermediate wall between two of said compartments, a first pair of separable contacts disposed in a first of said compartments adjacent one end thereof, a first tripping means disposed in said first compartment adjacent the other end thereof and operative to effect separation of said first pair of contacts upon flow of excessive current therethrough, a second pair of separable contacts disposed in a second of said compartments adjacent one end thereof, a second tripping means disposed in said second compartment adjacent the other end thereof and operative to effect separation of said second pair of contacts upon fiow of excessive current therethrough, and actuating means disposed in a third of said compartments, said first and second tripping means also being operable to effect separation of said first and second pairs of contacts upon operation of said actuating means, said actuating means including an electrical coil disposed in said third compartment adjacent one end thereof corresponding respectively to said one end of said first and second compartments, and said coil being energizable to effect operation of said actuating means and said first and second tripping means and separation of said first and second pairs of contacts upon occurrence of a predetermined potential difference across said coil.

4. A molded-case electrical circuit breaker comprising a casing having at least two side-by-side compartments each having a pair of opposite ends, a pair of separable contacts disposed in a first of said compartments adjacent one end thereof, a first pivotally mounted, spring-biased, releasably latchable trip lever disposed in said first compartment and releasable from a latched position for movement toward a tripped position to effect separation of said contacts, tripping means disposed in said first compartment adjacent the other end thereof for releasably latching said first trip lever, said tripping means being operative to release said first trip lever from said latched position upon flow of excessive current through said contacts, a second pivotally mounted, spring-biased, releasably latchable trip lever disposed in a second of said compartments, latching means disposed in said second compartment for releasably latching said second trip lever, actuating means disposed in said second compartment and operable to actuate said latching means and release said second trip lever, said actuating means including an electrical coil disposed in said second compartment adjacent one end thereof corresponding to said one end of said first compartment, said coil being energizable to effect operation of said actuating means to actuate said latching means and release said second trip lever upon occurrence of a predetermined potential difference across said coil, and a pivotally mounted common trip bar extending transversely of said compartments and operable upon release of either of said trip levers to effect release of the other of said trip levers.

5. A molded-case electrical circuit breaker as claimed in claim 4, wherein said actuating means also includes a core and a pivotally mounted armature, said armature having a first portion on one side of its pivotal axis attractable toward said core and a second portion on the other side of its pivotal axis movable to actuate said latching means upon attraction of said first portion toward said core.

6. A molded-ease electrical circuit breaker comprising a casing having at least three separately molded casing portions secured to each other and collectively defining at least two side-by-side compartments each having a pair of opposite ends, two of said casing portions respectively forming a pair of opposite outer side walls of said casing and a third of said casing portions forming an intermediate wall between said two compartments, a pair of separable contacts disposed in a first of said compartments adjacent one end thereof, a first pivotally mounted, spring-biased, releasably latchable trip lever disposed in said first compartment and releasable from a latched position for movement toward a tripped position to effect separation of said contacts, tripping means disposed in said first compartment adjacent the other end thereof for releasably latching said first trip lever, said tripping means being operative to release said first trip lever from said latched position upon flow of excessive current through said contacts, a second pivotally mounted, spring-biased, releasably latchable trip lever disposed in a second of said compartments, latching means disposed in said second compartment for releasably latching said second trip lever, actuating means disposed in said second compartment and operable to actuate said latching means and release said second trip lever, said actuating means including an electrical coil disposed in said second compartment adjacent one end thereof corresponding to said one end of said first compartment, said coil being energizable to effect operation of said actuating means to actuate said latching means and release said second trip lever upon occurrence of a predetermined potential difference across said coil, and a pivotally mounted common trip bar extending transversely of said compartments and operable upon release of either of said trip levers to effect release of the other of said trip levers.

7. A molded-case electrical circuit breaker comprising a casing having four separately molded casing portions secured to each other and collectively defining three sideby-side compartments each having a pair of opposite ends, two of said casing portions respectively forming a pair of opposite outer side walls of said casing and each of the other two of said casing portions forming an intermediate wall between two of said compartments, a first pair of separable contacts disposed in a first of said compartments adjacent one end thereof, a first pivotally mounted,

spring-biased, releasably latchable trip lever disposed in said first compartment and releasable from a latched position for movement toward a tripped position to effect separation of said first pair of contacts, a first tripping means disposed in said first compartment adjacent the other end thereof for releasably latching said first trip lever, said first tripping means being operative to release said first trip lever from said latched position upon flow of excessive current through said first pair of contacts, a second pair of separable contacts disposed in a second of said compartments adjacent one end thereof, a second pivotally mounted, spring-biased, releasably latchable trip lever disposed in said second compartment and releasable from a latched position for movement toward a tripped position to eifect separation of said second pair of contacts, a second tripping means disposed in said second compartment adjacent the other end thereof for releasably latching said second trip lever, said second tripping means being operative to release said second trip lever from said latched position upon flow of excessive current through said second pair of contacts, a third pivotally mounted, spring-biased, releasably latchable trip lever disposed in a third of said compartments, latching means disposed in said third compartment for releasably latching said third trip lever, actuating means disposed in said third compartment and operable to actuate said latching means and release said third trip lever, said actuating means including an electrical coil disposed in said third compartment adjacent one end thereof corresponding respectively to said one end of said first and second compartments, said coil being energizable to effect operation of said actuating means to actuate said latching means and release said third trip lever upon occurrence of a predetermined potential difference across said coil, and a pivotally mounted common trip bar extending transversely of said three compartments and operable upon release of any of said trip levers to effect release of the other two of said trip levers.

8. An electrical circuit breaker as claimed in claim 7, wherein said casing is provided with a pair of plug-in type line terminals adjacent one end and a pair of load terminals adjacent the other end, said line terminals being electrically connected respectively to stationary contacts of said first and second pairs of separable contacts and said load terminals being electrically connected respectively to said first and second tripping means, and said casing is provided adjacent said other end with a pair of terminals electrically connected to said coil in said third compartment.

9. A molded-case electrical circuit breaker as claimed in claim 1 wherein said coil occupies space in said second compartment corresponding to the space in said first compartment occupied by said contacts.

References Cited UNITED STATES PATENTS 7/1965 Clilford 2OO-51 6/1966 Klein 200-116 US. Cl. X.R. 335-13 

1. A MOLDED-CASE ELECTRICAL CIRCUIT BREAKER COMPRISING A CASING HAVING AT LEAST TWO SIDE-BY-SIDE COMPARTMENTS EACH HAVING A PAIR OF OPPOSITE ENDS, A PAIR OF SEPARABLE CONTACTS DISPOSED IN A FIRST OF SAID COMPARTMENTS ADJACENT ONE END THEREOF, TRIPPING MEANS DISPOSED IN SAID FIRST COMPARTMENT ADJACENT THE OTHER END THEREOF, SAID TRIPPING MEANS BEING OPERATIVE TO EFFECT SEPARATION OF SAID CONTACTS UPON FLOW OF EXCESSIVE CURRENT THERETHROUGH, AND ACTUATING MEANS DISPOSED IN A SECOND OF SAID COMPARTMENTS, SAID TRIPPING MEANS ALSO BEING OPERABLE TO EFFECT SEPARATION OF SAID CONTACTS UPON OPERATION OF SAID ACTUATING MEANS, SAID ACTUATING MEANS INCLUDING AN ELECTRICAL COIL DISPOSED IN SAID SECOND COMPARTMENT ADJACENT ONE END THEREOF CORRESPONDING TO SAID ONE END OF SAID FIRST CON- 